Throwaway tip and throwaway-type cutting tool

ABSTRACT

A throwaway-type cutting tool including a tool body having a distal end, and a plurality of throwaway tips mounted to the distal end. Each of the plurality of throwaway tips including a plate of a substantially rectangular shape. The plate has a corner angle of two adjacent corner cutting edges of a first side in a surface being to 90° or less, and two opposing ridges on the first side including the two adjacent corner cutting edges are defined as cutting edges which are in a non-parallel orientation to each other. Each of the plurality of throwaway tips have a cutting edge arranged to project toward the distal end. The two adjacent corner cutting edges on the first side in each of the plurality of throwaway tips are arranged to project toward an outer periphery of the distal end of the tool body.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a throwaway tip and a throwaway-typecutting tool, such as an end-mill, to which the throwaway tip ismounted.

The disclosure of Japanese Application No. H11-230916, 2000-160902,2000-180438 is hereby incorporated by reference into the presentapplication.

2. Description of the Related Art

Hitherto, in some throwaway-type end mills in which a plurality of, forexample, two, parallelogram plate-like throwaway tips are mounted to thedistal end of a tool body, and which are capable of performing a boringoperation, one tip has been arranged so that a long cutting edge isdefined as a front cutting edge and a short cutting edge is defined asan outer peripheral cutting edge, and the other tip has been arranged sothat a short cutting edge and a long cutting edge is defined as a frontcutting edge and a long cutting edge is defined as an outer peripheralcutting edge.

In this case, if the two tips have the same shape and size, they areconveniently administered or replaced. When such an end mill is used fora shoulder-cutting operation or a drilling operation with the outerperipheral cutting edges provided along the rotation axis of the toolbody, for example, when the front cutting edge of one tip is provided sothat an outer-peripheral corner-side cutting edge is projected at thedistal end to gradually incline inward to a base end, the inner cornercutting edge of the outer tip will project toward the distal end fromthe outer-peripheral-corner-side cutting edge, so that the front cuttingedge is easily chipped at low speed.

In order to overcome such a drawback, when the front cutting edge of theother tip is arranged in a radial direction so as to prevent the innercorner cutting edge from projecting toward the distal end, since theouter peripheral cutting edge of the other tip is inclined inward fromthe outer peripheral cutting edge of one tip and does not serve as theouter peripheral cutting edge, the outer peripheral cutting edgeperforms cutting with a single edge of one tip so that the front cuttingedge is easily chipped and cutting efficiency is low.

As an invention for improving such a defect, Japanese Unexamined PatentApplication Publication No. 10-291115 discloses an end mill. In the endmill two types of parallelogram plate-like tips are used, which are inline symmetry and are rotated in opposite directions. A short cuttingedge of one tip is used as a front cutting edge, and a long cutting edgeof the other tip is used as a front cutting edge thereby adopting anarrangement such that an outer peripheral corner-side cutting edge ofeach of the front cutting edges is projected toward the distal end froman inner corner cutting edge. This can perform a cutting operation usingouter peripheral corner-side cutting edges as two cutting edges, and canimprove cutting efficiency by restricting chipping of theouter-peripheral-corner-side cutting edges.

In such a end mill, however, two types of tips having different outershapes should be prepared, thereby making administration and replacementcomplicated, running costs increase, and the cost of manufacturing thetip increase.

SUMMARY OF THE INVENTION

In consideration of these actual circumstances, it is an object of thepresent invention to provide a throwaway tip including a plurality oftypes of cutting edges capable of arranging different cutting edgesthereon.

It is another object of the present invention to provide a cutting toolcapable of projecting outer peripheral corner-side cutting edges towardthe distal and thereof using one type of throwaway tip.

According to the present invention, there is provided a throwaway tipformed in substantially the shape of a rectangular shape in which acorner angle of two adjacent corner cutting edges of one side in onsurface (3) is set to 90° or less, and two opposing ridges on one sideincluding these corner cutting edges are defined as cutting edges whichare not parallel to each other.

In a case where a plurality of such throwaway tips are used and providedat the distal end of a tool body so that the two corner cutting edges onone side are located at the outer periphery of the distal end, ifcutting edges on one side sandwiching the corner cutting edges areprovided as outer peripheral cutting edges along the rotation axis ofthe tool body, the other cutting edges sandwiching the corner cuttingedges are inclines as front cutting edges from the outer peripherytoward the inside, so that front cutting edges, outer peripheral cuttingedges, and the outer-peripheral-side corner cutting edges can bearranged as two cutting edges. These cutting edges are difficult to chipand cutting efficiency is high, and the tips can be easily stored.

According to the present invention, there is provided a throwaway-typecutting tool comprising a plurality of throwaway tips mounted to thedistal end of a tool body, and each throwaway tip having a cutting edgearranged to project toward the distal end, wherein the plurality ofthrowaway tips are the same as one another according to any one ofclaims 1 to 4, and the two adjacent corner cutting edges on one side ineach of the plurality of throwaway tips are arranged to project towardthe outer periphery of the distal end of the tool body.

If the two corner cutting edges on one side are provided at the outerperiphery of the distal end of the tool body, cutting can be startedfrom the outer-peripheral-side corner cutting edges and chipping can berestricted when performing a drilling operation or the like, and whenperforming a shoulder-cutting operation or a groove-processingoperation, a finishing operation can be performed by the corner cuttingedges at the outer periphery of the distal end while performing theshoulder-cutting operation by the outer peripheral cutting edges.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings.

FIG. 1( a) is a plan view which shows a throwaway tip according to afirst embodiment of the present invention.

FIG. 1( b) is a side view, as seen from the direction A in FIG. 1( a).

FIG. 1( c) is a side view, as seen from the direction B in FIG. 1( a).

FIG. 2 is a partial side view of an end mill to which two throwaway tipsshown in FIG. 1 are mounted.

FIG. 3 is a front view of the end mill shown in FIG. 2.

FIG. 4 is a side view of the end mill shown in FIG. 2, as seen from thedirection of an outer peripheral cutting edge

FIG. 5 is a side view of an end mill according to a second embodiment ofthe present invention

FIG. 6 is a side view of the end mill shown in FIG. 5, a seen from thedirection C1.

FIG. 7 is a side view of the end mill shown in FIG. 5, as seen from thedirection D1.

FIG. 8( a) is a plan view which shows a throwaway tip according to athird embodiment of the present invention

FIG. 8( b) is a side view of a tip shown in FIG. 8( a), as seen from thedirection E1.

FIG. 8( c) is a side view of a tip shown in FIG. 8( a), as seen from thedirection F1.

FIG. 8( d) is a side view of a tip shown in FIG. 8( a), as seen from thedirection G1.

FIG. 9 is a front view of an end mill shown in FIG. 8 to which thethrowaway tip shown in FIG. 8 is mounted.

FIG. 10 is a side view of the end mill shown in FIG. 8, as seen from thedirection of one outer peripheral cutting edge

FIG. 11 is a side view of the end mill shown in FIG. 8, as seen from thedirection of the other outer peripheral cutting edge

FIG. 12( a) is a front view which shows another example of an end millto which a throwaway tip is mounted.

FIG. 12( b) is a front view which shows another example of an end millto which a throwaway tip is mounted.

FIG. 12( c) is a front view which shows another example of an end millto which a throwaway tip is mounted.

FIG. 12( d) is a front view which shows another example of an end millto which a throwaway tip is mounted.

FIG. 13( a) is a plan view of a throwaway tip according to amodification of the third embodiment.

FIG. 13( b) is a side view of a tip shown in FIG. 13( a) as seen fromthe direction H1.

FIG. 13( c) is a side view of a tip shown in FIG. 13( a) a as seen fromthe direction I1.

FIG. 13( d) is a side view of a tip shown in FIG. 13( a) as seen fromthe direction J1.

FIG. 13( e) is a side view of a tip shown in FIG. 13( a), as seen fromthe direction K1.

FIG. 14 is a plan view which shows a throwaway tip according to an 4thembodiment of the present invention.

FIG. 15 is an side view of an end mill according to an 5th embodiment ofthe present invention.

FIG. 16 is a plan view of an throwaway tip according to an 5thembodiment of the present invention.

FIG. 17( a) is an line sectional view which shows cross sectioned formof each part of a throwaway tip shown in FIG. 16.

FIG. 17( b) is an M—M line sectional view of FIG. 16.

FIG. 18 is a principal part side view of an end mill shown in FIG. 16 towhich two throwaway tips are mounted.

FIG. 19 is a front view of an end mill shown in FIG. 18.

FIG. 20 is a side view of the end mill shown in FIG. 18, as seen of thedirection of peripheral cutting edge.

FIG. 21 is a side view of the end mill according to an 6th embodiment ofthe present invention

FIG. 22 is a side view of an end mill shown in FIG. 21, as seen from thedirection of C2.

FIG. 23 is a side view of an end mill shown in FIG. 21, as seen from thedirection of D2.

FIG. 24( a) is a plan view of the throwaway tip according to the 7thembodiment of the present invention.

FIG. 24( b) is a side view of the tip shown in FIG. 24( a), as seen fromthe direction of E2.

FIG. 24( c) is a side view of the tip shown in FIG. 24( a), as seen fromthe direction of F2.

FIG. 24( d) is a side view of the tip shown in FIG. 24( a), as seen fromthe direction of G2.

FIG. 25 is a front view of an end mill shown in FIG. 24 to which thethrowaway tip is mounted.

FIG. 26 is a side view of an end mill shown in FIG. 25, as seen from thedirection of one outer peripheral cutting edge.

FIG. 27 is a side view of an end mill shown in FIG. 25, as seen from thedirection of the other outer peripheral cutting tooth

FIG. 28( a) is a plan view of a throwaway tip according to amodification of the 7th embodiment.

FIG. 28( b) is a side view of a tip shown in FIG. 28( a), as seen fromthe direction of H2.

FIG. 28( c) is a side view of a tip shown in FIG. 28( a), as seen fromthe direction of I2.

FIG. 28( d) is a side view of a tip shown in FIG. 28( a), as seen fromthe direction of J2.

FIG. 28( e) is a side view of a tip shown in FIG. 28( a), as seen fromthe direction of K2.

FIG. 29 is a front view of a throwaway tip according to the 8thembodiment of the present invention.

FIG. 30 is a side view of an end mill according to the 8th embodiment ofthe present invention.

FIG. 31 is a sectional view which shows sectional form of each part ofthrowaway tip according to the 9th embodiment of the present invention.

FIG. 32 is a sectional view which shows sectional form of each part ofthe throwaway tip according to 10 the embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A throwaway tip and throwaway-type end mill according to embodiments ofthe present invention will now be described with reference toaccompanying drawings. FIG. 1 shows a throwaway tip according to a firstembodiment, and FIGS. 2 to 4 show a throwaway-type end mill according tothe first embodiment. FIG. 1( a) is a plan view of the throwaway tip,FIG. 1( b) is a side view of the throwaway tip shown in FIG. 1( a), asseen from a direction A, FIG. 1( c) is a side view of the same, as seenfrom a direction B, FIG. 2 is a partial side view of the end mill towhich the throwaway tip shown in FIG. 1 is mounted, FIG. 3 is a frontview of the end mill shown in FIG. 2, and FIG. 4 is a partial side viewof the end mill shown in FIG. 2, as seen from an outer peripheralcutting edge.

The throwaway tip (hereinafter, it may be referred to as tip) 1according to the embodiment shown in FIG. 1 is formed in substantiallythe shape of a rectangular plate, includes an upper surface 3 providedso as to oppose a lower surface 2 constituting a seating surface, andfour side faces 4 gradually inclined outward with a positive inclinationangle (relief angle) from the lower surface 2 to the upper surface 3,and is defined as a positive tip. The tip 1 is formed with abolt-securing insertion hole 5 passing through central portions of theupper surface 3 and the lower surface 2. The upper surface 3 and thelower surface 2 are formed in substantially the shape of a parallelogramplate. In four ridges of the upper surface 3, the opposing ridges ofeach pair are defined as short cutting edges and long cutting edges, oneof two cutting edges constituting the short cutting edges is defined asa relatively-long first short cutting edge 6, and the other cutting edgeis defined as a relatively-short second cutting edge 7. The other twoopposing sides constituting the long cutting edges are defined as, forexample, a first long cutting edge 8 and a second long cutting edge 9that are relatively longer than the first short cutting edge 6.Moreover, the opposing first short cutting edge 6 and the second shortcutting edge 7 are not parallel to each other, and the other opposingfirst and second long cutting edges 8 and 9 are not parallel to eachother. The upper surface 3 is defined as a rake face of each of thecutting edges 6, 7, 8, and 9, and each of the side faces 4 is defined asa relief face.

A first corner cutting edge 10 and a second corner edge 11 in onediagonal direction of the upper surface 3 are formed by the intersectingfirst short cutting edge 6 and the first long cutting edge 8, and theintersecting second short cutting edge 7 and the second long cuttingedge 9 respectively, and each of the corner angles is set to 90° orless, preferably, an acute angle, a corner angle of a third cornercutting edge 12 consisting of the first short cutting edge 6 and thesecond long cutting edge 9 in the other diagonal direction is set to90°, and preferably, an acute angle, and a corner angle of a fourthcorner cutting edge 13 consisting of the second short cutting edge 7 andthe first long cutting edge 8 is set to an obtuse angle. The cornerangles of the first to third corner cutting edges 10, 11, and 12 may beeither equal or unequal to one another.

The throwaway tip 1 of this embodiment is constructed as describedabove. An end mill 20 to which a plurality of throwaway tips 1 aremounted will now be described with reference to FIGS. 2 to 4.

At the distal end of a tool body 21 of the end mill 20, two concavegrooves 22 and 23 are provided, which substantially oppose each otherwith respect to the rotation axis O defining the center of rotation andwhich are cut out into substantially a fan-shape in cross section. Theconcave grooves 22 and 23 are formed by cutting out the tool body 21from a longitudinal outer peripheral surface in the middle thereoftoward a distal end surface 21 a, a tip-mounting seat 24 a is formed ona surface of one concave groove 22 facing a rotation direction, atip-mounting seat 24 b is formed on a surface of the other concavegroove 23 facing the rotation direction.

To one tip-mounting seat 24 a, the above-described throwaway tip 1 ismounted with the second long cutting edge 9 defined as a front cuttingedge and projected from the distal end surface 21 a of the tool body 21toward the distal end, and this tip is referred to as a main tip 1A. Tothe other tip-mounting seat 24 b, the throwaway tip 1 is mounted withthe first short cutting edge 6 defined as a front cutting edge andprojected from the distal end surface 21 a of the tool body 21 towardthe distal end, and this tip is referred to as a sub-tip 1B. A state inwhich the first and second long cutting edges 8 and 9 are arranged in adirection to intersect the rotation axis O, as in the main tip 1A, isreferred to as a lateral arrangement, and a state in which the first andsecond long cutting edges 8 and 9 are arranged in a direction along therotation axis O, as in the sub-tip 1B, is referred to as a verticalarrangement.

In the main tip 1A, since the third corner cutting edge 12 is providedoutside the distal end, the first short cutting edge 6 is provided sothat it projects along the outer peripheral surface of the tool body 21to be substantially in parallel with the rotation axis O, and is definedas an outer peripheral cutting edge, the second long cutting edge 9projecting from the distal end surface 21 a of the tool body 21 towardthe distal end is inclined at an angle αα(for example, αα=5°) withrespect to the line perpendicular to the rotation axis O so that itgradually comes close to the base end side from the outer peripherytoward the rotation axis O, the second corner cutting edge 11 definingthe acute angle of the other end of the second long cutting edge 9 islocated on the opposite side of the rotation axis O, and the secondshort cutting edge 7 intersects the rotation axis O.

In the sub-tip 1B, since the first corner edge 10 is provided outsidethe distal end, the first long cutting edge 8 is provided so that itprojects along the outer peripheral surface of the tool body 21 to besubstantially in parallel with the rotation axis O and is defined as anouter peripheral cutting edge, the first short cutting edge 6 projectingfrom the distal end face 21 a of the tool body 21 toward the distal endis inclined at an angle ββ(for example, ββ=7 to 10°, ββ=αα isacceptable) so that it gradually comes close to the base end side fromthe outer periphery toward the rotation axis O, and the third cuttingedge 13 of the other end is separated away from the rotation axis O.

For this reason, the second short cutting edge 7, the second longcutting edge 9, and side faces 4 and 4 thereof located inside both tips1A and 1B are gradually inclined outward from the distal end toward thebase end in the direction away from the rotation axis O.

The main tip 1A and the sub-tip 1B are mounted in such a manner that thefirst axial rake angle of the first short cutting edge 6 and the firstlong cutting edge 8 defining each of the outer peripheral cutting edgesis a positive angle, as shown in FIG. 4 (only the first long cuttingedge 8 is shown in FIG. 5). As shown in FIG. 2, the second long cuttingedge 9 defining the front cutting edge of the main tip 1A is located onthe radial line around the rotation axis O, a radial rake angle is setto 0°, the first short cutting edge 6 defining the front cutting edge ofthe sub-tip 1B is located above the center of rotation of the tool body,and a radial rake angle is set to a negative angle.

Since the throwaway tip 1 and the end mill 20 according to thisembodiment are constructed as described above, if a material to be cutis cut by rotating the tool body 21 around the rotation axis O, thecorner cutting edges 12 and 10 on the outer periphery of the second longcutting edge 9 and the first cutting edge 6 projecting at the distal endof the tool body 21 bite into the material to be cut. Since this area isrotated at high speed as compared with an area near the rotation axis Ocutting resistance during biting is low and a cutting operation can beperformed without causing chipping. Furthermore, by feeding the toolbody 21 to an end of the rotation axis O, a rotary cutting operation canbe performed like a drill with the second long cutting edge 9 and thefirst short cutting edge 6 whose rotation paths overlap.

By feeding the tool body 21 in the lateral direction, outer peripheralcutting can be performed with the first short cutting edge 6 and thefirst long cutting edge 8 defining the outer peripheral cutting edges,and a finish cutting operation can be performed with the corner cuttingedges 12 and 10 of the second long cutting edge 9 and the first shortcutting edge 6. Alternatively, a shoulder-cutting operation or agroove-processing operation can be performed with the first cutting edge6 and the long cutting edge 8 defining the outer peripheral cuttingedges.

Even if the cutting edges of one of the tips 1A and 1B are chipped orworn, the same throwaway tips 1 may be replaced and mounted.

As described above, according to this embodiment, a plurality of thesame tips 1 can be mounted to the tool body with different mountingangles and in different postures so that the second long cutting edge 9and the first short cutting edge 6 can be arranged as front cuttingedges, and the short cutting edge 6 and the long cutting edge 8 can bearranged as outer peripheral cutting edges, and only one type ofreplacement tip need be stored. Therefore, the cost of manufacturing thetips and the running costs of the cutting tool can be reduced.

Moreover, since the corner angle of at least the first and third cornercutting edges 10 and 12 on both sides of the first short cutting edge 6is set to 90° or less, for example, an acute angle, the corner cuttingedges 10 and 12 at an outer-peripheral-side of the distal end of themain tip 1A and the sub-tip 1B can be provided in a state of beingprojected greatest, and since the corner cutting edges 10 and 12 can bearranged as two cutting edges whose rotation paths overlaps withrestricting the chipping of the corner cutting edges 10 and 12, thecutting efficiency is high. In addition, the side faces 4 inside themain tip 1A and the sub-tip 1B are gradually inclined from the distalend of the tool body 21 toward the base end in the direction away fromthe rotation axis O. Therefore, the thickness of a center portion 26 ofthe distal end of the tool body 21 sandwiched by the tips 1A and 1B canbe increased and ensured, and the rigidity of the tool body 21 can besecured.

A second embodiment of the present invention will now be described withreference to FIGS. 5 to 7. The same or similar portions to those of theabove-described first embodiment are indicated by the same referencenumerals and a description thereof will be omitted. FIG. 5 is a sideview of a throwaway-type end mill according to the second embodiment.

FIG. 6 is a side view of the end mill shown in FIG. 5, as viewed fromthe direction C, and FIG. 7 is a side view of the same, as viewed fromthe direction D. A throwaway-type end mill 30 shown in FIGS. 5 to 7according to the second embodiment has the same construction as thethrowaway-type end mill 20 according to the above-described firstembodiment. At the distal end of a tool body 21, two concave grooves 31and 32 are provided, which substantially oppose each other with respectto the rotation axis O defining the center of rotation and which are cutout into substantially a fan-shape in cross section. The concave grooves31 and 32 have tip-mounting seats 24 a and 24 b formed on the distal endsurfaces thereof facing a rotation direction, and a main tip 1A and asub-tip 1B are attached thereto, respectively. The arrangement of thetips 1A and 1B is the same as the above-described first embodiment.

In one concave grooves 31, a tip-mounting seat 31 a is further formed atthe base end side of the main tip 1A, and the above-described throwawaytip 1 is attached thereto as a third tip 1C. The third tip 1C isprovided in such a manner that a second long cutting edge 9 is projectedas an outer peripheral cutting edge from the outer peripheral surface ofthe tool body 21 to the outside in the radial direction so as to belocated substantially in parallel with the rotation axis O, and a secondshort cutting edge 7 is directed to the distal end.

An axial rake angle of the second long cutting edge 9 is set to apositive angle, as shown in FIG. 6, and the second long cutting edge 9is shifted toward the base end from a first long cutting edge 8 definingan outer peripheral cutting edge of the sub-tip 1B that is located onthe opposite position across the rotation axis O of the tool body 21 sothat its rotation path overlaps the rotation path of the first longcutting edge 8. Moreover, the first short cutting edge 6 of the main tip1A and the second long cutting edge 9 of the third tip 1C each definingan outer peripheral cutting edge are twisted rearward in the rotationdirection of the tool body 21 from the distal end toward the base end.

In the other concave groove 32, a tip-mounting seat 31 b is furtherformed at the base end side of the sub-tip 1B, and the above-describedthrowaway tip 1 is attached thereto as a fourth tip 1D. The fourth tip1D is provided in such a manner that the first long cutting edge 8 isprojected as an outer peripheral cutting edge from the outer peripheralsurface of the tool body 21 to the outside in the radial direction so asto be located substantially in parallel with the rotation axis O, andthe first short cutting edge 6 is directed to the distal end.

An axial rake angle of the first long cutting edge 8 is set to apositive angle, as shown in FIG. 7, and the first long cutting edge 8 isshifted toward the base end from a second long cutting edge 9 definingan outer peripheral cutting edge of the third 1C that is located on theopposite position across the rotation axis O of the tool body 21 so thatits rotation path overlaps the rotation path of the second long cuttingedge 9. Moreover, the first long cutting edge 8 of the sub-tip 1B andthe first long cutting edge 8 of the fourth tip 1D each defining anouter peripheral cutting edge are twisted rearward in the rotationdirection of the tool body 21 from the distal end toward the base end.

According to the end mill 30 of the second embodiment, the main tip 1Alocated at the distal end of the tool body 21 is arranged in thevertical direction so that the first short cutting edge 6 defines anouter cutting edge, and the sub-tip 1B is arranged in the lateraldirection so that the first long cutting edge 8 defines an outerperipheral cutting edge. Therefore the third tip 1C and the fourth tip1D can be arranged at the base end side of the main tip 1A and thesub-tip 1B so that the rotation paths of the outer peripheral cuttingedges continue, and a deep hole processing can be performed. Moreover,this can be achieved by using the tips 1A, 1B, 1C and 1D that are thesame as one another.

The number of the tips 1 arranged is not necessarily four, and three ormore than five tips may be arranged. Furthermore, in accordance with thearrangement of the main tip 1A in relation to the third tip 1C, sincethe first long cutting edge 8 located at the base end side of the maintip 1A is gradually inclined to the distal end from the outer peripheryof the tool body 21 toward the rotation axis O, and the second shortcutting edge 7 of the third tip 1C is inclined to the base end from theouter periphery toward the rotation axis O, the thickness of an outerperipheral portion 27 between the tips 1A and 1C can be increased fromthe outer periphery toward the inside. Therefore, the strength of thetool body 21 can be secured together with the strength of a centerportion 26 of the distal end thereof.

In FIGS. 5 to 7, one or both of the third tip 1C may be arranged in thelateral direction, and the first short cutting edge 6 and/or the secondshort cutting edge 7 may be defined as outer peripheral edges.Alternatively, the third tip 1C and the fourth tip 1D may be turnedupside down and arranged in the vertical direction, and the first longcutting edge 8 and the second long cutting edge 9 may be defined asouter peripheral cutting edges. In short, the tips may be arrangedeither in the vertical direction or in the lateral direction as long asthey can be arranged so that the rotation paths of the peripheralcutting edges overlap.

Another example of the throwaway tip of the present invention will nowbe described as a third embodiment. The same or similar portions tothose of the throwaway tip 1 according to the first embodiment will bedescribed using the same reference numerals.

FIG. 8( a) is a plan view of a throwaway tip according to thisembodiment, FIG. 8( b) is a side view of the throwaway tip shown in FIG.8 (a, as seen from the direction E. FIG. 8( c) is a side view of thesame, as seen from the direction F, and FIG. 8( d) is a side view of thesame, as seen from the direction G.

A throwaway tip (hereinafter, it may be referred to as tip) 40 shown inFIG. 8 according to the third embodiment is formed in substantially theshape of a rectangular plate, an upper surface 41 which opposes a lowersurface 2 defining a seating surface is formed in a planar shape whichis inclined from a first short cutting edge 6 toward an opposing secondshort cutting edge 7 so that the distance between the upper surface 41and the lower surface 2 is gradually shortened, and therefore, a firstlong cutting edge 8 and a second long cutting edge 9 are straight-linedcutting edges inclined from the first short cutting edge 6 toward thesecond short cutting edge 7. Therefore, the distance between the firstshort cutting edge 7 and the lower surface 2 is formed shortest. Aninsertion hole 5 passing through the upper and lower surfaces 41 and 2is formed in a direction to intersect nearly perpendicularly to thelower surface 2. Alternatively, the insertion hole 5 may be made tointersect perpendicularly to the upper surface 41. In mounting such atip 40 to the above-described end mill 30 (20) instead of the tip 1, ifthe tip 40 is mounted so that an radial rake angle or an axial rakeangle of each cutting edge is not changed, the thickness of tip-mountingseats 24 a, 24 b, 31 a, and 32 a formed on the back of the tip can beincreased and the strength of a tool body 21 can be increased. In a maintip 40A shown in FIG. 9 and a third tip 40C shown in FIG. 10, thethickness of the tip-mounting seats 24 a and 31 a on the side of thesecond short cutting edge 7 can be increased. When the tip 40 or 1 ismounted to the tip-mounting seat without changing the posture of theseating surface (lower surface 2, in a sub-tip 40B and a fourth tip 40Din which a first short cutting edge 6 is located at the distal end, asshown in FIG. 11, an axial rake angle of a first long cutting edge 8serving as an peripheral cutting edge can be increased, and the cuttingquality in the outer peripheral cutting can be improved.

In mounting the tip 1 according to the first embodiment and the tip 40according to the third embodiment to an end mill, the arrangement of thetips 1 and 40 is not limited to one form in which the main tips 1A and40A are arranged in the lateral direction at the distal end of the toolbody 21 and the sub-tips 1B and 40B are arranged in the verticaldirection, as shown in the end mill 20 and 30 of the first and secondembodiments, and other suitable arrangement forms may be adopted.

For example, in FIG. 12( a), if two tips 1 and 1 (40 and 40) arearranged in the lateral direction to define first short cutting edges 6and 6 as outer peripheral cutting edges and define second long cuttingedges 9 and 9 as front cutting edges, this arrangement form can beadopted to a tool body 21 having a large outer diameter. An end mill 50can be applied to a large-diameter-hole drilling operation. In an endmill 60 shown in FIG. 12( b), one tip 1 is arranged in the lateraldirection to define a first short cutting edge 6 as an outer peripheralcutting edge and define a second long cutting edge 9 as a front cuttingedge overlapping the rotation axis O and the other tip is arranged inthe vertical direction to define a second short cutting edge 7 as afront cutting edge and define a second long cutting edge 9 as an outerperipheral cutting edge. In an end mill 70 shown in FIG. 12 (c), twotips 1 and 1 (40 and 40) are arranged in the vertical direction todefine each first short cutting edge 6 as a front cutting edge anddefine each first long cutting edge 8 as an outer peripheral cuttingedge.

In an end mill 80 shown in FIG. 12( d) two tips 1 and 1 (40 and 40) arearranged in the vertical direction to define each second short cuttingedge 7 as a front cutting edge and define each second long cutting edge9 as an outer peripheral cutting edge. In an end mill 90 shown in FIG.12( e), both two tips 1 and 1 (40 and 40) are arranged in the verticaldirection to define a first short cutting edge 6 of one tip 1 as a frontcutting edge, define a first long cutting edge 8 as an outer peripheralcutting edge, define a second short cutting edge 7 of the other tip 1 asa front cutting edge, and define a second long cutting edge 9 as anouter peripheral cutting edge. In this case, in the end mills 50, 70,80, 90, a portion left uncut (a core remainder) is produced between thetwo tips 1 and 1 during cutting, but the portion can be picked up by theend mills if the thickness of the core remainder of a material to be cutis small. If the end mills are fed in the lateral direction, the portionleft uncut can be cut off. Since the second long cutting edge 9 of onetip 40 overlaps the rotation axis O in the end mill 60, no coreremainder is produced.

A throwaway tip may have a construction shown in FIG. 13 as amodification of the tip 40 according to the third embodiment. FIG. 13(a) is a plan view of a throwaway tip according to this modification,FIG. 13 (b) is a side view of the throwaway tip shown in FIG. 13( a), asseen from the direction H1, FIG. 13( c) is a side view of the same, asseen from the direction I1, FIG. 13( d) is a side view of the same, asviewed from the direction J1, and FIG. 13( e) is a side view of thesame, as viewed from the direction K1.

A throwaway tip 43 according to a modification shown in FIG. 13 isformed in substantially the shape of a rectangular plate, an uppersurface 44 which opposes a lower surface 2 defining a seat surface isformed into a twisted surface, and therefore, a first short cutting edge9, a second short cutting edge 7, a first long cutting edge 8, and asecond long cutting edge 9 are linear-shaped cutting edges inclined atan arbitrary angle so that the distance between the lower surface 2 andthese cutting edges gradually changes from one end of each of the cornercutting edges toward the other end. An insertion hole 5 passing throughthe upper and lower surfaces 44 and 2 is formed in a direction tointersect nearly perpendicularly to the lower surface 2. The insertionhole may be made to intersect perpendicularly to the upper surface 44.

The adoption of such a construction can set a suitable radial rake angleand an axial rake angle according to the mounting position or theposture of each cutting edge.

Breaker grooves may be formed in the upper surfaces 3, 41, 44.

The front cutting edges of the two tips 1 and 1 (40 and 40, 43 and 43)may be provided at a position above the center of rotation of the toolbody or at a position below the center of rotation of the tool body.

In the tips 1, 40, 44 of the third embodiments, the corner angles of thefirst and third corner cutting edges 10, 11, and 12 may be either equalor unequal to one another.

While the long cutting edges 8 and 9 and the short cutting edges 6 and 7in the throwaway tips of the above-described first and third embodimentsand the modification are straight-lined cutting edges, they may beinstead convexly curved cutting edges or concavely curved cutting edges,In this case, the upper surfaces 41 and 44 may be convex surfaces orconcave surfaces.

The throwaway tip according to the present invention may be mounted tovarious types of cutting tools, such as other types of rolling tools orturning tools without being limited to the end mills 30, 50, 60, 70, 80,and 90.

[4th embodiment] The 4th embodiment in this invention is explained inFIG. 14 and FIG. 15. The explanation is omitted using the same marks ina same or similar portions to those of above mentioned 2nd embodiment.FIG. 14 is a plane view of the throwaway tip according to the 4thembodiment, FIG. 15 is side view of an end mill of throwaway typeaccording to the 4th embodiment. Throwaway tip 96 shown in FIG. 14 isthe one that the sub-cutting tooth 97 is formed with the inclination tothe other portions so that it may retreat inside the field 3 of 1 as itapproaches the third corner tooth 12 in the end portion including thethird corner tooth 12 of the second long tooth 9, in a throwaway tip 1according to 1 st embodiment shown in FIG. 1.

The angle θ (for example θ=5°) inclination of the sub-cutting tooth 97is done to other portions of the second long tooth 9.

The throwaway type end mill 98 according to the 4th embodiment isequipped with the same construction as the throwaway type end mill 30according to above mentioned the 2nd embodiment, the tip 96 is replacedwith a tip 1. In a tip part of the main part 21 of a tool, Two concavegrooves 31, 32 which cut and lacked in the cross-sectional practicallysector are formed, almost opposite to rotation axis O which makes therotation center. In a tip side of each concave grooves 31, 32, the tipattachment seats 24 a, 24 b are formed in the field where each concavegrooves 31, 32 turn to the rotation direction, and it is equipped withmain tip 96A and sub-tip 96B respectively. The arrangement constructionof these tips 96A, 96B is the same as the arrangement construction ofthe tips 1A and 1B in the second embodiment mentioned above. And inabove mentioned arrangement construction, the sub-cutting tooth 97formed in the second long tooth 9 of tip 96A is projected to the tipside of the main part 21 of a tool rather than other portions of thesecond long tooth 9. Moreover, the second long tooth 9 of a tip 96B islocated in the inner circumference side of the main part 21 of a tool,and don't act on cutting. And the tip attachment seat 31 a is furtherformed in the base edge side of main tip 96A in the other concave groove31, and the throwaway tip 96 mentioned above is equipped as the thirdtip 96C. This third tip 96C is projected to the out side of radiusdirection from the perimeter face of the main part 21 of the tool as theperimeter tooth of the second long tooth 9, and is located almostparallel to the rotation axis O, and is set toward the second shorttooth 7 in a tip side. In this attachment construction, the sub-cuttingtooth 97 formed in a third tip 96C has escaped to the innercircumference side of a main part 21 of a tool to other portions of thesecond long tooth 9. Next, tip attachment seat 31 b is also formed in abase side of sub-tip 96B in the other concave groove 32, and thethrowaway tip 96 mentioned above is set as the fourth tip 96D. Thisfourth tip 96D is projected to outer side of radius direction from themain part 21 of a tool as the perimeter tooth of the first long tooth 8,and is located almost parallel to the rotation axis O, and is set towardthe first short tooth 6 in the tip side.

In this construction, the second long tooth 9 of a tip 96D is located inthe inner circumference side of a main part 21 of a tool, don't act oncutting. According to end mill 98 by this fourth embodiment, thesub-cutting tooth 97 of a tip 96A can be used in a finish cutting in athrowaway tip 96, and the sub-cutting tooth 97 in a tip 96B, 96C, 96Ddon't act on a cutting of work material. Thus, in end mill 98, since theadvance of the wear of sub cutting tooth 97 is prevented except the useof the second long tooth 9 as front face tooth, the throwaway tip 96 cansecure the sharpness of the sub-cutting tooth 97, and when it uses thesub-cutting tooth 97 as a front face tooth and performs finish machiningof a work material, it can aquire a good finished surface. Moreover, intip 96D located in the most base edge side of a main part 21 of a tool,since the first long tooth 8 which is not formed sub-cutting tooth 97 asa perimeter tooth is used, it can be possible to hold the maximumcutting of depth S of throwaway type cutting tool, forming sub-cuttingtooth 97 in the second long tooth 9.

In addition, the arrangement number of sheets of a tip 96 is notnecessarily four sheets, three sheets or more than five sheets may beset.

Moreover, in the fourth embodiment mentioned above, although thethrowaway tip 96 shall consist of having formed the sub-cutting tooth 97in the second long tooth 9 in a throwaway tip 1 by the first embodimentshown in FIG. 1, not only limiting in this, it may consist of formingthe sub-cutting tooth 97 in the second long tooth 9 in a throwaway tip40 or 43. Moreover, you may equip not only end mill 98 but also otherend mill with the throwaway tip 96.

[5th embodiment]although the throwaway tip and throwaway type end millby the 5th embodiment of this invention are explained with the referenceto a drawings, the explanation is omitted by using the same marks in aportion of the same or similar parts to each embodiment mentioned above.FIG. 16 and FIG. 17 show the throwaway tip by the 5th embodiment, andFIG. 18 to FIG. 20 show the throwaway type end mill by the 5thembodiment. FIG. 16 is a plan view of a throwaway tip, and FIG. 17 is across-sectional view of each part of the throwaway tip shown in FIG. 16.(a) is L—L line cross-sectional view in FIG. 16, (b) is M—M linecross-sectional view in FIG. 16. FIG. 18 is a principal part side viewof end mill which equipped with the throwaway tip shown in FIG. 16, andFIG. 19 is a front view of end mill shown in FIG. 18, FIG. 20 aprincipal part side view which looked at the end mill shown in FIG. 18from the perimeter tooth side. The throwaway tip (it may be hereaftercalled a tip) 101 by the embodiment shown in FIG. 16 and FIG. 17 is madeinto the shape of an approximately square plate like by which thearrangement and form of the under face 2, upper face, the four side face4, insert hole 5 are made almost the same as the throwaway tip 1 by 1stembodiment. Moreover, in four edge side on a upper face 3 of a tip 101,a each pair of edge side which opposite each other, is made a shorttooth and long tooth same as tip 1, one side of the cutting tooth of twotooth which constitutes a short tooth is taken as the first short tooth6 which it is comparatively long, the other is made the second shorttooth 7 which is comparatively short. The two side which opposite to theother which constitute the long tooth is made the first long tooth 8 andthe second long tooth 9 which is longer than the first short tooth 6.And the first short tooth 6 and the second short tooth 7 which oppositeeach other is made non-parallel, and the first long tooth 8 and thesecond long tooth 9 which opposite each other is also made non-parallel.The upper face 3 is made into the rake face of each cutting tooth 6, 7,8, 9, and the side face is made into the flank face. Moreover, in upperface 3, the land parts 14 which stands in a row in each cutting tooth isformed all over the circumferences. And, the first corner tooth 10 ofone direction of a diagonal of the upper face 3 and the second cornertooth 11 is formed by crossing of the first short tooth 6 and the firstlong tooth 8, the second short tooth 7 and the second long tooth 9respectively, and the third corner tooth 12 which consist of the firstshort tooth 6 and the second long tooth 9 of the another diagonaldirection and the fourth corner tooth 13 which consist of the secondshort tooth 7 and the first long tooth 8 is formed. The corner angle ofeach corner tooth is made as the almost same corner angle as the tip 1by the 1 st embodiment respectively. In this throwaway tip 101, the partof fourth corner tooth 13 slippage of the first long tooth 8 and thepart of the second corner tooth 11 slippage of the second long tooth 9,the strengthening part 15 is formed respectively. As shown in asectional view of FIG. 17( a), the strengthening part 15 formed in thefirst long tooth 8 is constructed as that the rake angle γ 1 (the firstrake angle) of a land part 14 in a portion of the fourth corner tooth 13slippage in the first long tooth 8 and a rake angle γ 2 (the second rakeangle) on a upper face 3 is made into a small angle than a rake angle γ3 of a land part 14 in other part of the first long tooth 8 and a rakeangle γ 4 on a upper face 3. (refer to the FIG. 17( b)). Similarly, inthe second long tooth 9, the strengthening part 15 is constructed asthat the rake angle γ 1 of a land part 14 in a part of the second cornertooth 11 slippage and a rake angle γ 2 of a upper face 3 is made into asmall angle than the rake angle γ 3 of a land part 14 in other part ofthe second long tooth 9 and a rake angle γ 4 on a upper face 3. Thestrengthening part 15 makes an rake angle into an smaller angle thanother parts, enlarges the thickness of the tooth and raises the strengthof the cutting tooth in this portion.

Here, In this first long tooth 8 and the second long tooth 9, the firstand the second rake angle in strengthened parts or parts other than astrengthened parts is good also as the same angle, and also let it be anangle different respectively. The throwaway tip 101 by this embodimentis constituted as mentioned above, the end mill 20 a which equipped withtwo or more of this throwaway tip 101 is explained by FIG. 18 to FIG.20. The end mill 20 a consists of the almost same composition as endmill 20 by the first embodiment, the throwaway tip 101 by thisembodiment is equipped on tip attachment seat 24 a, 24 b formed in a tippart of a main part 21 of a tool. And, the throwaway tip 101 mentionedabove is equipped at one tip attachment seat 24 a of the main part 21 ofa tool. The second long tooth 9 is projected to a tip side from the tipface 21 a of a main part 21 of a tool as the front face. This tip is as101A. In other tip attachment seat 24 b, the throwaway tip 101 isequipped projecting the first short tooth 6 from the tip face 21 a of amain part 21 of a tool as the front face tooth. This is as sub-tip 101B.(the arrangement of the main tip 101A and sub-tip 101B in end mill 20 aby this embodiment is almost made same as the main tip 1A and sub-tip 1Bin end mill 20 by the first embodiment shown in FIG. 18 to FIG. 20.)

With such arrangement construction, the strengthening part 15 of thesecond long tooth 9 which is a front face tooth of a main tip 101A islocated in a circumference side in a front face tooth. Moreover, thestrengthening part 15 of the first long tooth 8 which is perimeter toothof sub-tip 101B is located in a base edge side of a tool in a perimetertooth.

Since the throwaway tip 101 and end mill 20 a in this embodiment isconstructed as mentioned above, it can be possible to cut the workmaterial like the throwaway tip 1 and end mill 20 by the firstembodiment.

And, what is necessary to exchange the same throwaway tip 101 and justequip, even if the cutting tooth of one of the tips 101A and 101B issuffered a loss or worn out. Here, in conventional end mill, it isformed the overlapping part of rotation locus of perimeter tooth of twotips (the part becoming two number of tooth) and not overlapping part(the part becoming single tooth) in perimeter tooth of each throwawaytip when a main part of tool is rotated in a rotating axis line. Andcompared with the portion used as a two sheet edge, it is easy to damagethe portion which serves as a single edge in a cutting tooth in responseto strong cutting resistance at the time of cutting of work material.

In end mill 20 a of this embodiment, in each cutting work, the firstlong tooth 8 which is perimeter tooth of sub-tip 101B is not overlap thelocus of the first short tooth 6 which is perimeter tooth of main tip101A, this portion will cut the work material as a single tooth.

And in portions other than this, although the perimeter tooth of bothtips will cut the work materials as a two sheet edge, in these bothtips, the strengthening part 15 is formed in a part of single edge, andis secured the strength of the cutting tooth of this portion. And inboth tips, the selection of the shape of cutting tooth is not necessaryin other portion, and it can be possible to decrease the drop of thesharpness by taking the shape of cutting tooth which the sharpness ofcutting tooth is thought as important in this portion. According tothrowaway tip 101 and end mill 20 a which is constituted as this, inperimeter tooth of each tip 101, the strengthening part 15 is set in aportion of single tooth, as the results, the strength of cutting toothis secured, and it is possible to do the shape of cutting tooth wherethe sharpness was thought as important in a portion of two cuttingtooth, you may be possible to secure the strength of cutting tooth andto decrease the drop of the sharpness in a throwaway tip.

[the 6th embodiment] Although the 6th embodiment of this invention isexplained by FIG. 21 to FIG. 23, the explanation is omitted using thesame marks in a same or similar portion with each embodiments mentionedabove. FIG. 21 is a side view of an throwaway type end mill by the 6thembodiment, FIG. 22 is a C2 direction side view of the end mill shown inFIG. 21, FIG. 23 is also C2 direction side views.

The throwaway type end mill 30 a by the 6th embodiment shown in FIG. 21to FIG. 23 is equipped with the same construction as throwaway type endmill 20 a by the 5th embodiment, and in a tip portion of a main part 21of a tool, two concave groove 31, 32 which the cross section is cut inapproximately fan shape opposite to an rotation axis O which makes therotation center. The tip attachment seat 24 a, 24 b are formed in thefield where turn to the rotation direction in a tip side of each concavegroove 31 and 32, the main tip 101A, sub-tip 101B is equippedrespectively. The arrangement and construction of these tips 101A, 101Bis the same with the 5th embodiment mentioned above. And the tipattachment seat 31 a is further formed in the base edge side of a maintip 101A in the other concave groove, the throwaway tip 101 mentionedabove is equipped as the third tip 101C. This third tip 101C isprojected to the out side of radius direction from perimeter face of amain part 21 of a tool as the perimeter tooth of the second long tooth 9and is located in parallel to the rotation axis O, and is located towardthe second short tooth 7 in a tip side. With this arrangementcomposition, the strengthening portion 15 of the second long tooth 9which is the perimeter tooth of the third tip 101C is located in a tipside of a tool in a perimeter tooth. Moreover, this second long tooth 9is located in shifting to the base edge side from the first long tooth 8as that it overlaps the rotation locus of the first long tooth 8 whichmakes the perimeter tooth of sub-tip 101B located opposite to therotating axis O of a main part 21 of a tool. Next, in other concavegroove, the attachment seat 31 b is further formed in a base edge sideof a sub-tip 101B, the throwaway tip 101 mentioned above is equipped asthe fourth tip 101D. This fourth tip 101D is projected to out side ofradius direction from perimeter face of a main part 21 of a tool as theperimeter tooth of the first long tooth 8, and is located in a parallelto the rotating axis O, and is arranged turning the short tooth 6 to thetip side. With this arrangement composition, the strengthening portion15 of the first long tooth 8 which is the perimeter tooth of the fourthtip 101D is located in a base edge side of a tool in a perimeter tooth.Moreover, this first long tooth 8 is arranged shifting in a base edgeside from this second long tooth 9 which overlaps with the rotating axisof the second long tooth 9 which makes the perimeter tooth of the thirdtip 101C located opposite to the rotating axis O of a main part 21 of atool. Here, the arrangement of the tip 101A, 101B, 101C, 101D in endmill 30 a by this embodiment is made almost the same as that of 101A,101B, 101C, 101D in end mill 30 in the second embodiment.

In addition, the arrangement number of seats of a tip 101 is notnecessarily for seats, you may arrange three or five or more seats. Incase that the end mill 30 a is used in each cutting, the base edgeportion of tool of the first long tooth 8 which makes perimeter tooth ina sub-tip 101B and the tip portion of tool of the second long tooth 9which makes perimeter tooth in a third tip 101C and base edge portion ofa tool of the first long tooth 8 which makes perimeter tooth in a fourthtip 101D are not overlap with the locus of perimeter of other tiprespectively, and this portion will cut work material as a single toothrespectively. And in perimeter tooth of each tip, the other portion willcut the work material as a two sheet tooth.

Here, in each tip, the strengthening portion is formed in the portionused as single tooth, and the strength of this portion is secured. Andsince other portions do not need to add restriction to cutting toothshape in each tip, a fall of sharpness can be reduced as cutting toothshape where sharpness was thought as important.

According to the end mill 30 a by this 6th embodiment, the drop of thesharpness can be reduced, securing the the strength of cutting tooth ofa throwaway tip, since it can consider as the cutting tooth shape wheresharpness was thought as important in the portion used as a two sheettooth locating the strengthening part 15 in the portion used as a singletooth in the perimeter tooth of each throwaway tip 101.

[The 7th embodiment] The another embodiment of the throwaway tip in thisinvention is explained in FIG. 24 as the 7th embodiment, it is explainedby using the same mark about the same or similar portion with thethrowaway tip in above mentioned each embodiments.

FIG. 24( a) is a plan view of the throwaway tip by this embodiment, (b)is the E2 direction side view of the throwaway tip shown in (a), (c) isthe F2 direction side view similarly, (d) is the G2 direction side viewsimilarly. The throwaway tip 102 by the 7th embodiment shown in FIG. 24(it may be hereafter called a tip) is made into the shape ofapproximately square plate late, and the upper face 41 which countersthe under face 2 which is the seat face is formed to the plane likeinclined so that the distance with the under face 2 may become smallgradually towards the second short tooth 7, and therefore, the firstlong tooth 8 and the second long tooth 9 become linear like tooth fromthe first short tooth 6 toward the second short tooth 7. Therefore, inthe second short tooth 7, the distance with the under face 2 is formedto the smallest. Moreover, the penetrated hole 5 which penetrates thevertical sides 2 and 41 is punched in the direction which carries out analmost rectangular cross on the under face 2. Or you may it intersectperpendicularly with the upper face 41. Properly, the strengtheningportion 15 is constructed in a 4th corner tooth 13 slippage of the firstlong tooth 8 and a 2nd corner tooth 11 slippage of the second long tooth9 in this throwaway tip 102. In case that this throwaway tip 102 isequipped in an end mill 30 a (20) mentioned above in place of tip 101,if it is equipped not changing the radial rake angle and axial rakeangle of each tooth of each tip 102, it can be possible to enlarge thethickness of tip attaching seat 24 a, 24 b, 31 a, 32 a, of the back faceof tip, and the strength of tooth of a main part 21 of a tool can beimproved.

In main tip 102A shown in FIG. 25 and the third tip 102C shown in FIG.26, the thickness of the second short tooth 7 side of tip attaching seat24 a, 31 a can be thickened. Moreover, in case that it is equipped onattaching seat not changing the style of seat face (under face 2) of tip102 or 1, as shown in FIG. 27, the axial rake angle of the first longtooth 8 which is each perimeter tooth can be enlarged in sub-tip 102Band the 4th tip 102D which the first short tooth 6 is located in a tipportion side, and the sharpness of perimeter cutting can be improved.

You may have the composition shown in FIG. 28 as a modification of a tip102 by the 7th embodiment. FIG. 28( a) is a plan view of the throwawaytip by this embodiment, (b) is a H2 direction side view of the throwawaytip shown in (a, (c) is a I2 direction side view similarly, (d) is J2direction side view similarly, (e) is K2 direction side view similarly.

The throwaway tip 103 by the modification shown in FIG. 28 is made intoapproximately square plate late, and the upper face 44 which opposite tounder face 2 which makes seat face is formed in the twist face,therefore, the 1 st short tooth 6, the 2nd short tooth 7, the 1 st longtooth 8 and the 2nd long tooth 9 are the cutting tooth of the shape of astraight line which inclines at respectively voluntary angles so thatthe distance with the under face 2 may change gradually from the end ofa corner tooth towards the other corner edge respectively. Moreover, thepenetrating hole 5 which penetrate the vertical face 2, 44 is punched ina direction of approximately rectangular cross on the under face 2. Oryou may make it intersect perpendicularly with the upper face 44. Ifsuch composition is adopted, according to the attachment position andstyle of each cutting tooth, a suitable radial rake angle and a axialrake angle can be set up.

In addition, you may establish a breaker slot in the upper face 3, 41,44. Moreover, the each front face tooth of two sheets of tip 101, 101(102, 102; 103, 103) may be arranged in the position of core going up orcore going down. Moreover, in a tip 101, 102, 103 by the 5th and the 7thembodiment, the corner angle of the 1 st and three corner tooth 10, 11,12 of an acute angle is the same or may not be the same. In addition, ineach throwaway tip 101, 102, 103 by the 5th and the 7th embodiment, andmodification, each long tooth 8, 9, short tooth 6, 7 made into straightlike, in replace of this, convex curved like or concave curved like maybe good also, in this case, the upper face 41, 44 may be sufficient as aconvex curved face or concave curved face. Moreover, various cuttingtools such as other kind of milling tool, cutting tool by lathe can alsobe equipped with the throwaway tip by this invention without beinglimited to end mill 30 a.

[the 8th embodiment] The 8th embodiment in this invention is explainedby using FIG. 29 and FIG. 30, the explanation is omitted by using thesame mark in same or similar portion with the 6th embodiment mentionedabove. FIG. 29 is a plan view of the throwaway tip by the 8 thembodiment, FIG. 30 is the side view of throwaway type end mill by the8th embodiment. In the throwaway tip 101 by the 5th embodiment shown inFIG. 16, the throwaway tip 104 shown in FIG. 29 is the one that thesub-cutting tooth 97 which inclines so as to retreat inside of the face3 of 1 as it approaches the third corner tooth 12 is formed in a edgeportion including the third corner tooth 12 of the second long tooth 9.

The sub-cutting tooth 97 inclines at the angle θ (for example, θ=5°) tothe other portion of the second long tooth 9. The throwaway type endmill 98 a by the 8th embodiment is the same composition with thethrowaway type end mill 30 a by the 6th embodiment mentioned above, thetip 104 is arranged in replace of tip 101. In a tip portion of a mainpart 21 of a tool, two concave grooves 31, 32 which is cut inapproximately fan shape of cross-section opposite to rotation axis Owhich makes the rotation center.

The tip attachment seat 24 a, 24 b is formed in the face of rotationdirection in a tip side of each concave grooves 31, 32, the main tip104A and sub-tip 104B is equipped respectively. The arrangementcomposition of these tip 104A, 104B is the same that of the tip 101A,101B by the 6th embodiment mentioned above. And, In the arrangementcomposition mentioned above, the sub-cutting tooth 97 which is formed tothe second long tooth 9 of the tip 104A is projected to the tip side ofa main part 21 of a tool than the other portion of the second long tooth9. Moreover, the second long tooth 9 of the tip 104B is located innercircumference side of a main part 21 of a tool, and becomes not actingon cutting. And the tip attachment seat 31 a is also formed in the baseedge side of a main tip 104A in the other concave groove 31, thethrowaway tip 104 mentioned above is equipped as the third tip 104C.This third tip 104C uses the second long tooth 9 as a perimeter tooth,and it project to out side of radius direction from the perimeter faceof a main part 21 of a tool, and located almost parallel to rotationaxis O, and the second short tooth 7 is arranged towards tip side. Inthis arrangement composition, the sub-cutting tooth 97 which formed inthe third tip 104C is escaped to the inner side of the main part 21 oftool to the other portion of the second long tooth 9. Next, in the otherconcave groove 32, the tip attaching seat 31 b is also formed in a baseedge side of sub-tip 104B, and the throwaway tip 104 mentioned above isequipped as the 4th tip 104D. This 4th tip 104D uses the 1 st long tooth8 as perimeter tooth, and it projects to out side of radius directionfrom perimeter face of a main part 21 of a tool, and located in almostparallel to the rotation axis O, and the 1 st short tooth 6 is arrangedtowards tip side. In this arrangement composition, the second long tooth9 of the tip 104D is located in the inner circumference side of a mainpart 21 of a tool don't act on a cutting. According to the end mill 98 aby this 8th embodiment, the sub-cutting tooth 97 of a tip 104A can beused as a finish cutting in a throwaway tip 104, the sub-cutting tooth97 in other tip 104B, 104C, 104D don't act in cutting of work material.Thus, in end mill 98 a, since the proceeding of wear of sub-cuttingtooth 97 is restricted except the case that the second long tooth 9 isused as front face tooth, the sharpness of sub-cutting tooth 97 inthrowaway tip 104 can be secured, when it was done the finish machiningof work material by sub-cutting tooth 97 as the front face tooth, it canbe acquired a good finished surface. Moreover in tip 104D which locatedin the most base edge side of a main part 21 of a tool, since the firstlong tooth 8 not forming the sub-cutting tooth 97 is used as a perimetertooth, the maximum depth of cut S of throwaway type cutting tool can besecured, forming sub-cutting tooth 97 in second long tooth 9. Inaddition, the arrangement number of sheets is not necessarily foursheets, you may arrange three or more than five sheets. Moreover, in the8th embodiment mentioned above, the sub-cutting tooth 97 is constructedto the second long tooth 9 in throwaway tip 101 by the 5th embodimentshown in FIG. 16, however, for example, the sub-cutting tooth 97 isformed to the second long tooth 9 in either not only of this but thethrowaway tip 102 or 103. Moreover, the throwaway tip 104 may be notonly equipped with end mill 98 a but also other end mill.

[the 9th embodiment] the 9th embodiment of the throwaway tip in thisinvention as another example is shown in FIG. 31, it is explained byusing the same mark in a same or similar portion with the throwaway tip101 by the 5th embodiment. FIG. 31 is a sectional view showing thecross-sectioned form of each portion of throwaway tip in thisembodiment, (a) is a sectional view corresponding to L—L line sectionedview of throwaway tip by the 5th embodiment, (b) is a sectional viewcorresponding to M—M line sectioned view of throwaway tip by the 5thembodiment. The throwaway tip 105 (hereinafter, may be called as a tip)by the 9th embodiment shown in FIG. 31 has an almost same shape withthat of the throwaway tip 101 shown in FIG. 16, the circle honing isgiven in each cutting tooth. And it differs to the throwaway tip 101,the strengthening portion 15 of the first and second long tooth 8, 9 isnot made as small the rake angle to other portion, made as the followingcompositions.

Namely, the strengthening portion 15 of first long tooth 8 isconstructed as follows, as shown in a section view of FIG. 31, thecurvature radius R1 of the tip of tooth portion of second corner tooth11 slippage in the first long tooth 8 is made larger than that R2 of theother portion of the first long tooth 8 (refer to FIG. 31( b)).Similarly, the strengthening portion 15 in the second long tooth 9 isalso constructed so that the curvature radius of a tip of tooth of the4th corner tooth slippage R1 is made larger than that R2 of otherportion of the 1 st long tooth 8 (not shown in figure). Thestrengthening portion 15 is taking the curvature radius of the tip ofthe tooth larger than other portions, raises the cutting strength ofthis portion. Here, the curvature radius R1 of the strengthening portion15 comrades or the curvature radius R2 of other than strengtheningportion 15 is good also as the same with the first long tooth 8 and thesecond long tooth 9 and it can also consider as a curvature radiusdifferent, respectively. [the 10th embodiment] The 10th embodiment ofthe throwaway tip in this invention as another example is shown in FIG.32, it is explained by using the same mark about the same or similarportion with the throwaway tip 101 by the 5th embodiment. FIG. 32 is asectional view showing the cross-sectioned form of each portion ofthrowaway tip in this embodiment, (a) is a sectional view correspondingto L—L line sectioned view of the throwaway tip by 5th embodiment, (b)is a sectional view corresponding to M—M line sectioned view of thethrowaway tip by the 5th embodiment. The throwaway tip 106 (hereinaftermay be called as a tip) by the 10th embodiment shown in FIG. 32 is thealmost same as that of the throwaway tip 101 shown in FIG. 16. And itdiffers in the throwaway tip 101, the strengthening portion 15 of the 1st, 2nd long tooth 8, 9 is not made the rake angle to the other portionsmall, but considers as the as the compositions which is describedbelow. Namely, as shown in a sectional view of FIG. 32( a), the width W1of land portion 14 of the 2 nd corner tooth 11 slippage in the 1 st longtooth 8 is made larger than that W2 (refer to FIG. 25( b)) of the landpart 14 of the other portion of the 1st long tooth 8. Similarly, in thesecond long tooth 9, the strengthening portion 15 is constructed as thatthe width W1 of land part 14 of the 4th corner tooth 13 slippage is madelarger than that W2 of land part 14 of other portion of the 1 st longtooth 8 (not shown in figure). The strengthening portion 15 is takeingthe width W1 of the land part 14 larger than other portions, and raisesthe strength of the cutting tooth of this portion. Here, The width W1 ofthe land part 14 in each strengthening portion 15 with the 1 st longtooth 8 and 2nd long tooth 9 is made the same to the width W2 of landpart 14 of the other portion than the strengthening portion 15, or itcan also consider as width different, respectively. In addition, in tip102, 103, 104 by the 7th, 8th embodiment mentioned above, the examplewhich formed the strengthening portion 15 by the same composition withthe strengthening portion 15 of the throwaway tip 101 shown in the 5thembodiment, however, without being restricted to this, the compositionof the strengthening portion 15 is good also as which composition of thethrowaway tip 101, 105, 106 shown in the 5th, the 9th, the 10thembodiment, and is good also as what combined these composition. Thisinvention is not limited to each embodiments mentioned above, andincludes the various modifications also including the combination ofeach embodiment mentioned above.

1. A cutting tool comprising: a tool body having a distal end; and aplurality of tips mounted to the distal end of the tool body, each tipof the plurality of tips comprising a plate of substantiallyquadrilateral shape, the plate having a first corner having a cornerangle of less than 90° and an adjacent second corner having a cornerangle of less than 90°, wherein at least one of the first corner and thesecond corner is arranged to project along an outer periphery of thedistal end of the tool body, wherein: each tip of the plurality of tipshas two opposing cutting edges defined as long cutting edges and anothertwo opposing cutting edges defined as short cutting edges; one of thelong cutting edges in a first of the plurality of tips projectingtowards the distal end of the tool body is defined as a first frontperipheral cutting edge and one of the short cutting edges in the firstof the plurality of tips is defined as a first outer peripheral cuttingedge; and one of the short cutting edges in a second of the plurality oftips projecting towards the distal end of the tool body is defined as asecond front peripheral cutting edge and one of the long cutting edgesin the second of the plurality of tips is defined as a second outerperipheral cutting edge.
 2. The cutting tool of claim 1, wherein thefirst and second outer peripheral cutting edges are oriented such thatrotation paths of the first and second outer peripheral cutting edgesoverlap when the tool body is rotated around a rotation axis.
 3. A tipcomprising a first edge corner having a corner angle of less than 90°,and an adjacent second edge corner having a corner angle of less than90°, wherein the tip is formed of a substantially quadrilateral-shapedplate, and wherein said tip includes at least one edge corner having acorner angle of greater than 90°, wherein: said first edge corner isdefined by a first cutting edge and a second cutting edge; said firstcutting edge includes a main cutting tooth portion and a sub-cuttingtooth portion; said sub-cutting tooth portion is provided adjacent ajoint between said first cutting edge and said second cutting edge; saidsub-cutting tooth portion is slightly inclined with respect to maincutting tooth portion; and wherein said corner angle of said first edgecorner is defined as an angle between said main cutting tooth portion ofsaid first cutting edge and said second cutting edge.
 4. A cutting toolcomprising: a tool body having a distal end; and a plurality of tipsmounted to the distal end of the tool body, each tip of the plurality oftips comprising a plate of substantially quadrilateral shape, the platehaving a first corner having a corner angle of less than 90° and anadjacent second corner having a corner angle of less than 90°, whereinat least one of the first corner and the second corner is arranged toproject along an outer periphery of the distal end of the tool body,wherein: said first corner is defined by a first cutting edge and asecond cutting edge; said first cutting edge includes a main cuttingtooth portion and a sub-cutting tooth portion; said sub-cutting toothportion is provided adjacent a joint between said first cutting edge andsaid second cutting edge; said sub-cutting tooth portion is slightlyinclined with respect to main cutting tooth portion; and wherein saidcorner angle of said first corner is defined as an angle between saidmain cutting tooth portion of said first cutting edge and said secondcutting edge.
 5. A cutting tool comprising: a tool body having a distalend; and a plurality of tips mounted to the distal end of the tool body,each tip of the plurality of tips comprising a plate of substantiallyquadrilateral shape, the plate having a first corner having a cornerangle of less than 90° and an adjacent second corner having a cornerangle of less than 90°, wherein at least one of the first corner and thesecond corner is arranged to project along an outer periphery of thedistal end of the tool body, wherein: said tool body has an axis ofrotation; said plurality of tips comprises a first tip, a second tip, athird tip, and a fourth tip; said first tip and said third tip areprovided within a first groove on said tool body, said first tip andsaid third tip being provided at different locations along the axis ofrotation, said first tip and said third tip being spaced apart along theaxis of rotation; and said second tip and said fourth tip are providedwithin a second groove on said tool body, said second tip and saidfourth tip being provided at different locations along the axis ofrotation, said second tip and fourth tip being spaced apart along theaxis of rotation.
 6. The cutting tool of claim 5, wherein: said firsttip has a first outer peripheral cutting edge and the second tip has asecond outer peripheral cutting edge, said first outer peripheralcutting edge and said second outer peripheral cutting edge are orientedsuch that rotation paths of said first outer peripheral cutting edge andsaid second outer peripheral cutting edge overlap when said tool body isrotated around the rotation axis; said third tip has a third outerperipheral cutting edge and the fourth tip has a fourth outer peripheralcutting edge, said third outer peripheral cutting edge and said fourthouter peripheral cutting edge are oriented such that rotation paths ofsaid third outer peripheral cutting edge and said fourth outerperipheral cutting edge overlap when said tool body is rotated aroundthe rotation axis; a first space provided between said first outerperipheral cutting edge and said third outer peripheral cutting edge,said first space being oriented such that a rotation path of at leastone of said second outer peripheral cutting edge and said fourth outerperipheral cutting edge overlap with said first space when said toolbody is rotated around the rotation axis; a second space is providedbetween said second outer peripheral cutting edge and said fourth outerperipheral cutting edge, said second space being oriented such that arotation path of at least one of said first outer peripheral cuttingedge and said third outer peripheral cutting edge overlap with saidsecond space when said tool body is rotated around the rotation axis. 7.A tip comprising a substantially planar plate including a first edgecorner having a corner angle of less than 90°, and an adjacent secondedge corner having a corner angle of less than 90°, wherein the plateincludes at least one edge corner having a corner angle of greater than90°, wherein: said first edge corner is defined by a first cutting edgeand a second cutting edge; said first cutting edge includes a maincutting tooth portion and a sub-cutting tooth portion; said sub-cuttingtooth portion is provided adjacent a joint between said first cuttingedge and said second cutting edge; said sub-cutting tooth portion isslightly inclined with respect to main cutting tooth portion; andwherein said corner angle of said first edge corner is defined as anangle between said main cutting tooth portion of said first cutting edgeand said second cutting edge.
 8. A cutting tool comprising: a tool bodyhaving a distal end; a first tip mounted to the distal end of the toolbody, said first tip comprising a substantially planar plate including afirst edge corner having a corner angle of less than 90°, and anadjacent second edge corner having a corner angle of less than 90°,wherein at least one of the first edge corner and the second edge corneris arranged along an outer periphery of the distal end of the tool body;a second tip mounted to the distal end of the tool body, said second tipcomprising a plate including a first edge corner having a corner angleof less than 90°, and an adjacent second edge corner having a cornerangle of less than 90°, wherein at least one of the first edge cornerand the second edge corner of said second tip is arranged along theouter periphery of the distal end of the tool body; a third tip mountedto the distal end of the tool body, said third tip comprising a plateincluding a first edge corner having a corner angle of less than 90°,and an adjacent second edge corner having a corner angle of less than90°, wherein at least one of the first edge corner and the second edgecorner of said third tip is arranged along the outer periphery of thedistal end of the tool body; and a fourth tip mounted to the distal endof the tool body, said fourth tip comprising a plate including a firstedge corner having a corner angle of less than 90°, and an adjacentsecond edge corner having a corner angle of less than 90°, wherein atleast one of the first edge corner and the second edge corner of saidfourth tip is arranged along the outer periphery of the distal end ofthe tool body, wherein: each tip of said first tip, said second tip,said third tip, and said fourth tip have two opposing cutting edgesdefined as long cutting edges and another two opposing cutting edgesdefined as short cutting edges; one of said long cutting edges of saidfirst tip extends along the outer periphery; one of said short cuttingedges of said second tip extends along the outer periphery; one of saidlong cutting edges of said third tip extends along the outer periphery;and one of said long cutting edges of said fourth tip extends along theouter periphery.
 9. A cutting tool comprising: a tool body having adistal end; a first tip mounted to the distal end of the tool body, saidfirst tip comprising a substantially planar plate including a first edgecorner having a corner angle of less than 90°0, and an adjacent secondedge corner having a corner angle of less than 90°, wherein at least oneof the first edge corner and the second edge corner is arranged along anouter periphery of the distal end of the tool body; a second tip mountedto the distal end of the tool body, said second tip comprising a plateincluding a first edge corner having a corner angle of less than 90°,and an adjacent second edge corner having a corner angle of less than90°, wherein at least one of the first edge corner and the second edgecorner of said second tip is arranged along the outer periphery of thedistal end of the tool body; a third tip mounted to the distal end ofthe tool body, said third tip comprising a plate including a first edgecorner having a corner angle of less than 90°, and an adjacent secondedge corner having a corner angle of less than 90°, wherein at least oneof the first edge corner and the second edge corner of said third tip isarranged along the outer periphery of the distal end of the tool body;and a fourth tip mounted to the distal end of the tool body, said fourthtip comprising a plate including a first edge corner having a cornerangle of less than 90°, and an adjacent second edge corner having acorner angle of less than 90°, wherein at least one of the first edgecorner and the second edge corner of said fourth tip is arranged alongthe outer periphery of the distal end of the tool body, wherein: saidtool body has an axis of rotation; said first tip and said third tip areprovided within a first groove on said tool body, said first tip andsaid third tip being provided at different locations along the axis ofrotation, said first tip and said third tip being spaced apart along theaxis of rotation; and said second tip and said fourth tip are providedwithin a second groove on said tool body, said second tip and saidfourth tip being provided at different locations along the axis ofrotation, said second tip and fourth tip being spaced apart along theaxis of rotation.
 10. The cutting tool of claim 9, wherein: said firsttip has a first outer peripheral cutting edge and the second tip has asecond outer peripheral cutting edge, said first outer peripheralcutting edge and said second outer peripheral cutting edge are orientedsuch that rotation paths of said first outer peripheral cutting edge andsaid second outer peripheral cutting edge overlap when said tool body isrotated around the rotation axis; said third tip has a third outerperipheral cutting edge and the fourth tip has a fourth outer peripheralcutting edge, said third outer peripheral cutting edge and said fourthouter peripheral cutting edge are oriented such that rotation paths ofsaid third outer peripheral cutting edge and said fourth outerperipheral cutting edge overlap when said tool body is rotated aroundthe rotation axis; a first space provided between said first outerperipheral cutting edge and said third outer peripheral cutting edge,said first space being oriented such that a rotation path of at leastone of said second outer peripheral cutting edge and said fourth outerperipheral cutting edge overlap with said first space when said toolbody is rotated around the rotation axis; and a second space is providedbetween said second outer peripheral cutting edge and said fourth outerperipheral cutting edge, said second space being oriented such that arotation path of at least one of said first outer peripheral cuttingedge and said third outer peripheral cutting edge overlap with saidsecond space when said tool body is rotated around the rotation axis.11. A cutting tool comprising: a tool body having a distal end; and afirst tip mounted to the distal end of the tool body, said first tipcomprising a substantially planar plate including a first edge cornerhaving a corner angle of less than 90°, and an adjacent second edgecorner having a corner angle of less than 90°, wherein at least one ofthe first edge corner and the second edge corner is arranged along anouter periphery of the distal end of the tool body, and wherein theplate includes at least one edge corner having a corner angle of greaterthan 90°, wherein: said first edge corner is defined by a first cuttingedge and a second cutting edge; said first cutting edge includes a maincutting tooth portion and a sub-cutting tooth portion; said sub-cuttingtooth portion is provided adjacent a joint between said first cuttingedge and said second cutting edge; said sub-cutting tooth portion isslightly inclined with respect to main cutting tooth portion; andwherein said corner angle of said first edge corner is defined as anangle between said main cutting tooth portion of said first cutting edgeand said second cutting edge.
 12. A cutting tool comprising: a tool bodyhaving a distal end; and a plurality of tips mounted to the distal endof the tool body, each tip of the plurality of tips comprising a plateof substantially quadrilateral shape, the plate having a first cornerhaving a corner angle of less than 90° and a second corner having acorner angle of less than 90°, wherein at least one of the first cornerand the second corner is arranged to project along an outer periphery ofthe distal end of the tool body, wherein: each tip of the plurality oftips has two opposing cutting edges defined as long cutting edges andanother two opposing cutting edges defined as short cutting edges; oneof the long cutting edges in a first of the plurality of tips projectingtowards the distal end of the tool body is defined as a first frontperipheral cutting edge and one of the short cutting edges in the firstof the plurality of tips is defined as a first outer peripheral cuttingedge; and one of the short cutting edges in a second of the plurality oftips projecting towards the distal end of the tool body is defined as asecond front peripheral cutting edge and one of the long cutting edgesin the second of the plurality of tips is defined as a second outerperipheral cutting edge.